Monitoring orangutan reintroduction: Results of activity budgets, diets, vertical use and associations during the first year post-release in Kehje Sewen Forest, East Kalimantan, Indonesia

 

Author: FITRIAH  BASALAMAH1,2,5; SRI SUCI UTAMI ATMOKO2; DYAH PERWITASARI-FARAJALLAH1,3; IBNUL QAYIM1; JAMARTIN SIHITE4;  MARIA VAN NOORDWIJK5; ERIK WILLEMS5;  CAREL P. VAN SCHAIK5

  1. Department of Biology, Faculty of Mathematics and Natural Sciences, Institut Pertanian Bogor. Jl. Pajajaran, Kampus IPB Baranangsiang, Bogor 16151.
  2. Faculty of Biology and Primate Research Center, Universitas Nasional, Jakarta 12520, Indonesia
  3. Primate Research Center, Bogor Agricultural, Institut Pertanian Bogor. Bogor 16151, West Java, Indonesia
  4. Borneo Orangutan Survival Foundations (BOSF), Restoration Habitat of Orangutan Indonesia (RHOI). Bogor 16151, West Java, Indonesia
  5. Anthropologisches Institut und Museum, Universitat Zurich. 8006 Zurich, Switzerland

 

Abstract

Monitoring orangutan reintroduction: Results of activity budgets, diets, vertical use and associations during the first year post- release  in Kehje Sewen Forest,  East  Kalimantan,  Indonesia.  Biodiversitas 19:  609-620. Pongo  pygmaeus morio, a subspecies of orangutan  founded  east  Kalimantan  is  steadily  declining  and  classified  as  endangered.  A  reintroduction  program  was  recently established. We monitored the reintroduced individuals during their first year post-release at Kehje Sewen Forest in East Kalimantan to document the adjustment to their new habitat. Here, we present a report on the activity patterns, food choice, travel height, nest-building abilities and associations of six individuals ranging between eight and thirteen years old. Our results show that all individuals survived their first year. They spent most of their time feeding and had a largely frugivorous diet, similar to wild orangutans. However, although they were able to build nests, they reused or rebuilt old nests more often than expected. They also spent 16% of their total activity time on the ground, more than expected. This information will contribute to attempts to evaluate factors affecting the adjustment process, and thus optimizing future reintroduction procedures.

 

Keywords: Adjustment, daily activity, Pongo pygmaeus morio, reintroduction

 

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